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Accessing or navigating through the Qlik Sense Hub may show Engine related error messages.

The messages may vary and are not limited to:  

An error occurred No available Qlik Sense Engine Was found. Refresh your browser or contact your system administrator.
 

Connection to the Qlik Sense Engine failed for unspecified reasons. Refresh your browser or contact your system administrator

No Engine server is available for the following app app:_hub

No broker service available

An error has occurred


This article provided guidance on how to troubleshoot these issues, as well commonly known solutions.


Environment:

Qlik Sense any version 

Resolution:

The above errors indicate communication problems between the Qlik Sense Proxy service, the Qlik Sense Engine service, and the Qlik Sense Dispatcher service (also known as the Broker service).

Are the Qlik Sense services running?

• Connect to the server(s) supposed to run the Qlik Sense Engine Service to find out whether the service is up and running.
• Verify the same for the Dispatcher Service

Suggested Action: Try to restart those services

Can the Engine(s) be reached by the Management Service (QMC)?

• Open QMC and in Configure System go to Engines and make sure it/they are marked as running

Suggested Action: Try to restart those services and verify that all architecture requirements are met (see next step).

Architecture requirements

• See the Qlik Sense online documentation. ! Port allocations may vary depending on the deployment version due to different services available. Select the correct version. 
• Verify that an engine is attached to the Virtual Proxy that is serving the Qlik Sense Hub. 
  • Details on Load Balancing configuration can be found in the online documentation.
  • An example of the above: Hub Error: Connection to Qlik Sense engine failed for unspecified reasons
• Is the Qlik Sense Proxy configured with the correct WebSocket host white list?
  • Details on the WebSocket host white list can be found in the online documentation.
  • An example of the above: Error Message "An error occurred Connection lost" When Connecting To Qlik Sense Hub
• Is the WebSocket protocol allowed between the client machine and the Qlik Sense Engine Server through the network?
  • Follow the instruction in the following article to verify WebSocket availability: Qlik Sense Websocket Connectivity Tester

Log file analysis

• Gather the Qlik Sense log files using the Qlik Sense log collector. See How To Collect Qlik Sense Log Files
• Alternatively, the currently active Qlik Sense log files are by default stored in C:\Programdata\Qlik\Sense\Log (only applicable if file logging is enabled!)
• For more details on how the Qlik Sense file logging works, and where archived logs are stored, see How logging works in Qlik Sense.
• For details on what gets logged where, see Troubleshooting Qlik Sense using logs

Suggested actions: Review the logs with a timestamp of the encountered issue to find related error messages.  

Search the available Qlik knowledge bases 

Using the symptom and error messages found in the Qlik Sense log files, search the available knowledge bases

• Our Public Article Database (some more content available logged in from the Support Portal)
• The Qlik Community

Common symptoms and resolutions

Qlik Sense Repository and/or Proxy unable to perform operation due to buffer space
Hub Error: Connection to Qlik Sense engine failed for unspecified reasons
Connection to the Qlik Sense engine failed for unspecified reasons randomly on the hub

Log a Support Ticket

If the above did not help resolve the issue, or further investigation is required, please reach out to Qlik Support.

• Collect the Qlik Sense logs How To Collect Qlik Sense Log Files
  • Make sure that the Logging Level set in the QMC -> Engine -> Logging is set to INFO and DEBUG. We recommend to use DEBUG mode only for troubleshooting purpose. Under a loaded environment this mode can created instabilities. 
• Include at least one timestamp and UserID of when the issue was seen
• Include detailed symptoms of the problem, such as an error message, problem experienced by the end user or administrator, and a screen capture of the error message